[DOCS] Added link to product compatibility matrix
[DOCS] Added link to product compatibility matrix

Original commit: elastic/x-pack-elasticsearch@19f04e486f3087018b696771fcd06aaf7308515a

robin13/elasticsearch,gingerwizard/elasticsearch,nknize/elasticsearch,gfyoung/elasticsearch,GlenRSmith/elasticsearch,robin13/elasticsearch,scorpionvicky/elasticsearch,coding0011/elasticsearch,gfyoung/elasticsearch,GlenRSmith/elasticsearch,uschindler/elasticsearch,gfyoung/elasticsearch,robin13/elasticsearch,GlenRSmith/elasticsearch,GlenRSmith/elasticsearch,coding0011/elasticsearch,coding0011/elasticsearch,gingerwizard/elasticsearch,gfyoung/elasticsearch,HonzaKral/elasticsearch,nknize/elasticsearch,nknize/elasticsearch,uschindler/elasticsearch,gingerwizard/elasticsearch,coding0011/elasticsearch,robin13/elasticsearch,gingerwizard/elasticsearch,gingerwizard/elasticsearch,gfyoung/elasticsearch,scorpionvicky/elasticsearch,uschindler/elasticsearch,robin13/elasticsearch,GlenRSmith/elasticsearch,scorpionvicky/elasticsearch,coding0011/elasticsearch,gingerwizard/elasticsearch,gingerwizard/elasticsearch,HonzaKral/elasticsearch,HonzaKral/elasticsearch,nknize/elasticsearch,HonzaKral/elasticsearch,uschindler/elasticsearch,uschindler/elasticsearch,scorpionvicky/elasticsearch,nknize/elasticsearch,scorpionvicky/elasticsearch